The present invention relates to display apparatus and method for detecting positions of eyes of one or a plurality of observers and allowing a stereoscopic video image to be observed by a motion parallax of two eyes and, more particularly, to image display apparatus and method for enabling other observers except an observer of a stereoscopic video image to observe a two-dimensional video image.
Hitherto, as a stereoscopic display apparatus, an apparatus of a double-eye type is most known. FIG. 1 shows a conventional double-eye type stereoscopic display apparatus. As shown in FIG. 2, an image 206 for the right eye and an image 208 for the left eye are displayed on a screen 202 of a display apparatus 200. By using an auxiliary optical system such as polarization glasses or the like, the image 206 for the right eye is shown to a right eye 38 and, at the same time, the image 208 for the left eye is shown to a left eye 40. A stereoscopic image 204 is shown by a motion parallax of the two eyes. As a stereoscopic display apparatus which does not need the auxiliary optical system such as polarization glasses or the like, there are an apparatus of a lenticular system of FIG. 3 and an apparatus of a parallax barrier system of FIG. 4. The stereoscopic display apparatus of the lenticular system of FIG. 3 is constructed by a display 210 such as a liquid crystal device or the like and a lenticular lens 212. A display pixel R of the image for the right eye and a display pixel L of the image for the left eye are separately arranged on the display 210. A light from the right-eye pixel R is projected to a position of the right eye 38 of the observer in a sight region 214 by the lenticular lens 212. Simultaneously, a light from the left-eye pixel L is projected to a position of the left eye 40 of the observer in the sight region 214 by the lenticular lens 212, so that a stereoscopic video image can be seen by the motion parallax of the two eyes. A stereoscopic display apparatus of the parallax barrier system of FIG. 4 is constructed by the display 210 such as a liquid crystal device or the like and slits 216. The display pixel R of the image for the right eye and the display pixel L of the image for the left eye are separately arranged on the display 210. A light from the right-eye pixel R is projected to the position of the right eye 38 of the observer in the sight region 214 by the slits 216. Simultaneously, a light from the left eye pixel L is projected to the position of the left eye 40 of the observer in the sight region 214 by the slits 216. Consequently, a stereoscopic video image can be seen by the motion parallax of the two eyes.
However, with respect to both of the lenticular system and the parallax barrier system, when the positions of the eyes 38 and 40 of the observer are deviated from the preset sight region 214 as shown in eyes 38' and 40', since an opposite sight state in which the images entering the right and left eyes are exchanged occurs and the images are separated or the screen becomes dark, there is a problem such that a stereoscopic observing region is limited. As an apparatus for solving the problem, there is a stereoscopic display apparatus of FIG. 5 in which the stereoscopic observing region is enlarged with respect to the lenticular system. The stereoscopic display apparatus uses a double lenticular lens 220 in which the screen has slits 222. For the screen using the double lenticular lens 220, a display 216-1 and a projection lens 218-1 which are used for a right-eye image, and a display 216-2 and a projection lens 218-2 which are used for a left-eye image are independently provided in a projector 215. The double lenticular lens 220 has a function to transmit a light toward the incoming direction of the light. When the screen is seen from the position of the sight region 214 facing the projection lenses 218-1 and 218-2, therefore, the projected right-eye video image R and left-eye video image L can be seen. The video images can be respectively perceived by the right and left eyes 38 and 40 and can be observed as a solid. When the observer moves in a lateral direction 224-1 or a front/rear direction 226-1, the position of the projector 215 is moved in a lateral direction 224-2 or a front/rear direction 226-2 in accordance with the observer, thereby always preventing that the eyes 38 and 40 of the observer are deviated from the sight region 214.
In case of the conventional stereoscopic display apparatus of the lenticular system, however, a stereoscopic observing range called a sub-probe is also spread in the lateral direction of the sight region 214 for the sight region 214 that is set while tracing the observer. When the projector 215 is moved according to one observer, therefore, there is a problem such that a separating region of the video image is insufficient for another observer, for example, another person seeing from behind the observer, so that the image cannot be seen as a solid, and moreover, a quality of a two-dimensional image itself which can be seen also deteriorates. Even when a plurality of projectors 215 are prepared in correspondence to a plurality of observers, if the projectors 215 are moved differently according to the respective observers, an obstruction of the video images by the sub-probes occurs among the projectors, so that there is a problem such that the apparatus can cope with only one observer.